#include <nxos.h>
#include <stdio.h>
#include <string.h>
#include <strings.h>
#include <errno.h>
#include <stdlib.h>
#include <stdint.h>
#include <ctype.h>

#include <netsocket.h>

#define HOST_ADDR "192.168.0.200"

#define ISspace(x) isspace((int)(x))

#define SERVER_STRING "Server: jdbhttpd/0.1.0\r\n"

int AcceptRequest(int client);
void bad_request(int);
void cat(int client, NX_Solt resource);
void cannot_execute(int);
void error_die(const char *);
void execute_cgi(int, const char *, const char *, const char *);
int get_line(int, char *, int);
void headers(int, const char *);
void not_found(int);
void serve_file(int, const char *);
int startup(unsigned short *);
void unimplemented(int);

/**********************************************************************/
/* Get a line from a socket, whether the line ends in a newline,
 * carriage return, or a CRLF combination.  Terminates the string read
 * with a null character.  If no newline indicator is found before the
 * end of the buffer, the string is terminated with a null.  If any of
 * the above three line terminators is read, the last character of the
 * string will be a linefeed and the string will be terminated with a
 * null character.
 * Parameters: the socket descriptor
 *             the buffer to save the data in
 *             the size of the buffer
 * Returns: the number of bytes stored (excluding null) */
/**********************************************************************/
int get_line(int sock, char *buf, int size)
{
 int i = 0;
 char c = '\0';
 int n;

 while ((i < size - 1) && (c != '\n'))
 {
  //recv()包含于<sys/socket.h>,参读《TLPI》P1259, 
  //读一个字节的数据存放在 c 中
  n = NET_Recv(sock, &c, 1, 0);
  /* DEBUG printf("%02X\n", c); */
  if (n > 0)
  {
   if (c == '\r')
   {
    //
    n = NET_Recv(sock, &c, 1, MSG_PEEK);
    /* DEBUG printf("%02X\n", c); */
    if ((n > 0) && (c == '\n'))
     NET_Recv(sock, &c, 1, 0);
    else
     c = '\n';
   }
   buf[i] = c;
   i++;
  }
  else
   c = '\n';
 }
 buf[i] = '\0';

 return(i);
}

/**********************************************************************/
/* Give a client a 404 not found status message. */
/**********************************************************************/
void not_found(int client)
{
 char buf[1024];

 sprintf(buf, "HTTP/1.0 404 NOT FOUND\r\n");
 NET_Send(client, buf, strlen(buf), 0);
 sprintf(buf, SERVER_STRING);
 NET_Send(client, buf, strlen(buf), 0);
 sprintf(buf, "Content-Type: text/html\r\n");
 NET_Send(client, buf, strlen(buf), 0);
 sprintf(buf, "\r\n");
 NET_Send(client, buf, strlen(buf), 0);
 sprintf(buf, "<HTML><TITLE>Not Found</TITLE>\r\n");
 NET_Send(client, buf, strlen(buf), 0);
 sprintf(buf, "<BODY><P>The server could not fulfill\r\n");
 NET_Send(client, buf, strlen(buf), 0);
 sprintf(buf, "your request because the resource specified\r\n");
 NET_Send(client, buf, strlen(buf), 0);
 sprintf(buf, "is unavailable or nonexistent.\r\n");
 NET_Send(client, buf, strlen(buf), 0);
 sprintf(buf, "</BODY></HTML>\r\n");
 NET_Send(client, buf, strlen(buf), 0);
}

/**********************************************************************/
/* Inform the client that a request it has made has a problem.
 * Parameters: client socket */
/**********************************************************************/
void bad_request(int client)
{
 char buf[1024];

 sprintf(buf, "HTTP/1.0 400 BAD REQUEST\r\n");
 NET_Send(client, buf, sizeof(buf), 0);
 sprintf(buf, "Content-type: text/html\r\n");
 NET_Send(client, buf, sizeof(buf), 0);
 sprintf(buf, "\r\n");
 NET_Send(client, buf, sizeof(buf), 0);
 sprintf(buf, "<P>Your browser sent a bad request, ");
 NET_Send(client, buf, sizeof(buf), 0);
 sprintf(buf, "such as a POST without a Content-Length.\r\n");
 NET_Send(client, buf, sizeof(buf), 0);
}

/**********************************************************************/
/* Inform the client that the requested web method has not been
 * implemented.
 * Parameter: the client socket */
/**********************************************************************/
void unimplemented(int client)
{
 char buf[1024];

 sprintf(buf, "HTTP/1.0 501 Method Not Implemented\r\n");
 NET_Send(client, buf, strlen(buf), 0);
 sprintf(buf, SERVER_STRING);
 NET_Send(client, buf, strlen(buf), 0);
 sprintf(buf, "Content-Type: text/html\r\n");
 NET_Send(client, buf, strlen(buf), 0);
 sprintf(buf, "\r\n");
 NET_Send(client, buf, strlen(buf), 0);
 sprintf(buf, "<HTML><HEAD><TITLE>Method Not Implemented\r\n");
 NET_Send(client, buf, strlen(buf), 0);
 sprintf(buf, "</TITLE></HEAD>\r\n");
 NET_Send(client, buf, strlen(buf), 0);
 sprintf(buf, "<BODY><P>HTTP request method not supported.\r\n");
 NET_Send(client, buf, strlen(buf), 0);
 sprintf(buf, "</BODY></HTML>\r\n");
 NET_Send(client, buf, strlen(buf), 0);
}

/**********************************************************************/
/* Return the informational HTTP headers about a file. */
/* Parameters: the socket to print the headers on
 *             the name of the file */
/**********************************************************************/
void headers(int client, const char *filename)
{
 char buf[1024];
 (void)filename;  /* could use filename to determine file type */

 strcpy(buf, "HTTP/1.0 200 OK\r\n");
 NET_Send(client, buf, strlen(buf), 0);
 strcpy(buf, SERVER_STRING);
 NET_Send(client, buf, strlen(buf), 0);
 sprintf(buf, "Content-Type: text/html\r\n");
 NET_Send(client, buf, strlen(buf), 0);
 strcpy(buf, "\r\n");
 NET_Send(client, buf, strlen(buf), 0);
}

/**********************************************************************/
/* Put the entire contents of a file out on a socket.  This function
 * is named after the UNIX "cat" command, because it might have been
 * easier just to do something like pipe, fork, and exec("cat").
 * Parameters: the client socket descriptor
 *             FILE pointer for the file to cat */
/**********************************************************************/
void cat(int client, NX_Solt resource)
{
 char buf[1024];
  NX_SSize filesz;
  NX_Size nread;
  NX_FileStatInfo st;


  NX_FileGetStat(resource, &st);
  filesz = st.size;
  printf("server: cat file size: %d\n", filesz);
 
 //从文件文件描述符中读取指定内容
 nread = NX_FileRead(resource, buf, sizeof(buf));
 while (filesz > 0 && nread > 0)
 {
  NET_Send(client, buf, nread, 0);
  filesz -= nread;
  nread = NX_FileRead(resource, buf, sizeof(buf));
 }
}

/**********************************************************************/
/* Send a regular file to the client.  Use headers, and report
 * errors to client if they occur.
 * Parameters: a pointer to a file structure produced from the socket
 *              file descriptor
 *             the name of the file to serve */
/**********************************************************************/
void serve_file(int client, const char *filename)
{
 NX_Solt resource = NX_SOLT_INVALID_VALUE;
 int numchars = 1;
 char buf[1024];

  printf("server: file %s...\n", filename);

 //确保 buf 里面有东西，能进入下面的 while 循环
 buf[0] = 'A'; buf[1] = '\0';
 //循环作用是读取并忽略掉这个 http 请求后面的所有内容
 while ((numchars > 0) && strcmp("\n", buf))  /* read & discard headers */
  numchars = get_line(client, buf, sizeof(buf));

 //打开这个传进来的这个路径所指的文件
 resource = NX_FileOpen(filename, NX_FILE_RDONLY, 0);
 if (resource == NX_SOLT_INVALID_VALUE) {
  printf("server: file %s not found!\n", filename);
  not_found(client);
 }
 else
 {
  //打开成功后，将这个文件的基本信息封装成 response 的头部(header)并返回
  headers(client, filename);
  //接着把这个文件的内容读出来作为 response 的 body 发送到客户端
  cat(client, resource);
 }
 
 NX_FileClose(resource);
}

/**********************************************************************/
/* Execute a CGI script.  Will need to set environment variables as
 * appropriate.
 * Parameters: client socket descriptor
 *             path to the CGI script */
/**********************************************************************/
void execute_cgi(int client, const char *path,
                 const char *method, const char *query_string)
{
 char buf[1024];
 int i;
 char c;
 int numchars = 1;
 int content_length = -1;
 
  printf("server: file %s is cgi !\n", path);

 //往 buf 中填东西以保证能进入下面的 while
 buf[0] = 'A'; buf[1] = '\0';
 //如果是 http 请求是 GET 方法的话读取并忽略请求剩下的内容
 if (strcasecmp(method, "GET") == 0)
  while ((numchars > 0) && strcmp("\n", buf))  /* read & discard headers */
   numchars = get_line(client, buf, sizeof(buf));
 else    /* POST */
 {
  //只有 POST 方法才继续读内容
  numchars = get_line(client, buf, sizeof(buf));
  //这个循环的目的是读出指示 body 长度大小的参数，并记录 body 的长度大小。其余的 header 里面的参数一律忽略
  //注意这里只读完 header 的内容，body 的内容没有读
  while ((numchars > 0) && strcmp("\n", buf))
  {
   buf[15] = '\0';
   if (strcasecmp(buf, "Content-Length:") == 0)
    content_length = atoi(&(buf[16])); //记录 body 的长度大小
   numchars = get_line(client, buf, sizeof(buf));
  }
  
  //如果 http 请求的 header 没有指示 body 长度大小的参数，则报错返回
  if (content_length == -1) {
   bad_request(client);
   return;
  }
 }

 sprintf(buf, "HTTP/1.0 200 OK\r\n");
 NET_Send(client, buf, strlen(buf), 0);

  /* 创建一个双向管道 */
  NX_Solt pipe, child;

  pipe = NX_PipeCreate(NX_NULL, 4096, NX_PIPE_SEND | NX_PIPE_RECV);

  if (pipe == NX_SOLT_INVALID_VALUE)
  {
      NX_Printf("pipe create failed!\n");
      return;
  }

  /* 创建一个子进程，并重定向管道到标准输入输出 */
  child = NX_ProcessLaunch((char *)path, NX_THREAD_CREATE_SUSPEND, NX_NULL, (char *)path, NX_NULL);
  if (child == NX_SOLT_INVALID_VALUE)
  {
      NX_SoltClose(pipe);
      return;
  }

  /* 重定向管道 */
  NX_Solt newPipeSolt = NX_SoltCopyTo(child, pipe, 0);
  if (newPipeSolt != 0)
    abort();
  newPipeSolt = NX_SoltCopyTo(child, pipe, 1);
  if (newPipeSolt != 1)
    abort();
  
  /* TODO: 给子进程传入环境变量 */

  NX_ThreadResume(child);

  /* 如果是父进程，把数据写入管道 */
  if (strcasecmp(method, "POST") == 0)
   for (i = 0; i < content_length; i++) {
    NET_Recv(client, &c, 1, 0);
    NX_FileWrite(pipe, &c, 1);
  }

  /* 父进程等待管道输出结果，并写到网络客户端里面 */
  while (NX_FileRead(pipe, &c, 1) > 0)
  {
    NET_Send(client, &c, 1, 0);
  }
  
  /* 关闭管道 */
  NX_SoltClose(pipe);

  /* 等待子进程退出 */
  NX_Printf("wait child exit %d\n", NX_ThreadWait(child, NX_NULL));
}

int AcceptRequest(int client)
{
  char buf[1024];
  int numchars;
  char method[255];
  char url[255];
  char path[512];
  size_t i, j;
  int cgi = 0;      /* becomes true if server decides this is a CGI
                      * program */
  char *query_string = NULL;
  NX_FileStatInfo st;

  printf("SERVER: accept ok: %d\n", client);

  //读http 请求的第一行数据（request line），把请求方法存进 method 中
  numchars = get_line(client, buf, sizeof(buf));
  i = 0; j = 0;
  while (!ISspace(buf[j]) && (i < sizeof(method) - 1))
 {
  method[i] = buf[j];
  i++; j++;
 }
 method[i] = '\0';

 //如果请求的方法不是 GET 或 POST 任意一个的话就直接发送 response 告诉客户端没实现该方法
 if (strcasecmp(method, "GET") && strcasecmp(method, "POST"))
 {
  unimplemented(client);
  return -1;
 }

 //如果是 POST 方法就将 cgi 标志变量置一(true)
 if (strcasecmp(method, "POST") == 0)
  cgi = 1;

 i = 0;
 //跳过所有的空白字符(空格)
 while (ISspace(buf[j]) && (j < sizeof(buf))) 
  j++;
 
 //然后把 URL 读出来放到 url 数组中
 while (!ISspace(buf[j]) && (i < sizeof(url) - 1) && (j < sizeof(buf)))
 {
  url[i] = buf[j];
  i++; j++;
 }
 url[i] = '\0';

 //如果这个请求是一个 GET 方法的话
 if (strcasecmp(method, "GET") == 0)
 {
  //用一个指针指向 url
  query_string = url;
  
  //去遍历这个 url，跳过字符 ？前面的所有字符，如果遍历完毕也没找到字符 ？则退出循环
  while ((*query_string != '?') && (*query_string != '\0'))
   query_string++;
  
  //退出循环后检查当前的字符是 ？还是字符串(url)的结尾
  if (*query_string == '?')
  {
   //如果是 ？ 的话，证明这个请求需要调用 cgi，将 cgi 标志变量置一(true)
   cgi = 1;
   //从字符 ？ 处把字符串 url 给分隔会两份
   *query_string = '\0';
   //使指针指向字符 ？后面的那个字符
   query_string++;
  }
 }

 //将前面分隔两份的前面那份字符串，拼接在字符串htdocs的后面之后就输出存储到数组 path 中。相当于现在 path 中存储着一个字符串
 sprintf(path, "htdocs%s", url);
 
 //如果 path 数组中的这个字符串的最后一个字符是以字符 / 结尾的话，就拼接上一个"index.html"的字符串。首页的意思
 if (path[strlen(path) - 1] == '/')
  strcat(path, "index.html");
 
 //在系统上去查询该文件是否存在
 if (NX_FileGetStatFromPath(path, &st) != NX_EOK) {
  //如果不存在，那把这次 http 的请求后续的内容(head 和 body)全部读完并忽略
  while ((numchars > 0) && strcmp("\n", buf))  /* read & discard headers */
   numchars = get_line(client, buf, sizeof(buf));
  //然后返回一个找不到文件的 response 给客户端
  printf("server: file %s not found!\n", path);
  not_found(client);
 }
 else
 {
  printf("server: file %s found!\n", path);
  //文件存在，那去跟常量S_IFMT相与，相与之后的值可以用来判断该文件是什么类型的
  //S_IFMT参读《TLPI》P281，与下面的三个常量一样是包含在<sys/stat.h>
  if (NX_FILE_IS_DIR(st.mode))  
   //如果这个文件是个目录，那就需要再在 path 后面拼接一个"/index.html"的字符串
   strcat(path, "/index.html");

  /* 如果文件后缀是支持的CGI格式 */
  char *suffix = strrchr(path, '.');
  if (suffix != NULL) {
    suffix++;
    if (!strcmp(suffix, "cgi") || 
        !strcmp(suffix, "py") ||
        !strcmp(suffix, "xapp"))
      cgi = 1;
  }

  // force no cgi!
  // cgi = 0;

  if (!cgi)
   //如果不需要 cgi 机制的话，
   serve_file(client, path);
  else
   //如果需要则调用
   execute_cgi(client, path, method, query_string);
 }

  /* close before close */
  NET_Shutdown(client, SHUT_WR);
  NET_Close(client);
  return 0;
}
/** 255.255.255.255 */
#define INADDR_NONE         IPADDR_NONE
/** 127.0.0.1 */
#define INADDR_LOOPBACK     IPADDR_LOOPBACK
/** 0.0.0.0 */
#define INADDR_ANY          IPADDR_ANY
/** 255.255.255.255 */
#define INADDR_BROADCAST    IPADDR_BROADCAST

/**********************************************************************/
/* Print out an error message with perror() (for system errors; based
 * on value of errno, which indicates system call errors) and exit the
 * program indicating an error. */
/**********************************************************************/
void error_die(const char *sc)
{
 //包含于<stdio.h>,基于当前的 errno 值，在标准错误上产生一条错误消息。参考《TLPI》P49
 perror(sc); 
 exit(1);
}

/**********************************************************************/
/* This function starts the process of listening for web connections
 * on a specified port.  If the port is 0, then dynamically allocate a
 * port and modify the original port variable to reflect the actual
 * port.
 * Parameters: pointer to variable containing the port to connect on
 * Returns: the socket */
/**********************************************************************/
int startup(unsigned short *port)
{
 int httpd = 0;
 //sockaddr_in 是 IPV4的套接字地址结构。定义在<netinet/in.h>,参读《TLPI》P1202
 struct sockaddr_in name;
 
 //socket()用于创建一个用于 socket 的描述符，函数包含于<sys/socket.h>。参读《TLPI》P1153
 //这里的PF_INET其实是与 AF_INET同义，具体可以参读《TLPI》P946
 httpd = NET_Socket(AF_INET, SOCK_STREAM, 0);
 if (httpd < 0)
  error_die("socket");
  
 memset(&name, 0, sizeof(name));
 name.sin_family = AF_INET;
 //htons()，ntohs() 和 htonl()包含于<arpa/inet.h>, 参读《TLPI》P1199
 //将*port 转换成以网络字节序表示的16位整数
 name.sin_port = htons(*port);
 //INADDR_ANY是一个 IPV4通配地址的常量，包含于<netinet/in.h>
 //大多实现都将其定义成了0.0.0.0 参读《TLPI》P1187
 name.sin_addr.s_addr = htonl(INADDR_ANY);
 
 //bind()用于绑定地址与 socket。参读《TLPI》P1153
 //如果传进去的sockaddr结构中的 sin_port 指定为0，这时系统会选择一个临时的端口号
 if (NET_Bind(httpd, (struct sockaddr *)&name, sizeof(name)) != NX_EOK)
  error_die("bind");

#if 0
 //如果调用 bind 后端口号仍然是0，则手动调用getsockname()获取端口号
 if (*port == 0)  /* if dynamically allocating a port */
 {
  int namelen = sizeof(name);
  //getsockname()包含于<sys/socker.h>中，参读《TLPI》P1263
  //调用getsockname()获取系统给 httpd 这个 socket 随机分配的端口号
  if (getsockname(httpd, (struct sockaddr *)&name, &namelen) == -1)
   error_die("getsockname");
  *port = ntohs(name.sin_port);
 }
#endif
 //最初的 BSD socket 实现中，backlog 的上限是5.参读《TLPI》P1156
 if (NET_Listen(httpd, 5) != NX_EOK) 
  error_die("listen");
 return(httpd);
}

int WebServerTest(void)
{
int server_sock = -1;
 uint16_t port = 80; // default on 80
 //sockaddr_in 是 IPV4的套接字地址结构。定义在<netinet/in.h>,参读《TLPI》P1202
 struct sockaddr_in client_name;
 socklen_t client_name_len = sizeof(client_name);
 //pthread_t newthread;

 server_sock = startup(&port);
 printf("httpd running on port %d\n", port);

  while (1)
  {
      int conn = NET_Accept(server_sock,
                       (struct sockaddr *)&client_name,
                       &client_name_len);
      if (conn < 0)
      {
        printf("SERVER: accept err on sock: %d\n", server_sock);        
        printf("SERVER: exit on accept\n");
        break;
      }
      else
      {
        if (AcceptRequest(conn) < 0) {
          break;
        }
      }
  }
  NET_Shutdown(server_sock, SHUT_RDWR);
  NET_Close(server_sock);    
  printf("WebServer: exit on accept\n");
  return 0;
}

int main(int argc, char **argv)
{
  return WebServerTest();
}
